Dissipative Cyclic Reaction Networks: Mechanistic Insights into a Minor Enantiomer Recycling Process

An analysis of an out-of-equilibrium cyclic reaction network which continuously converts a minor undesired product enantiomer to the desired major enantiomer by irreversible addition of chemical fuel and irreversible elimination of spent fuel is presented. The reaction network is maintained as long as fuel is added; interrupted fuel addition drives the system towards equilibrium, but the cyclic process restarts upon resumed fuel addition, as demonstrated by three consecutive fuel cycles. The process is powered by the hydrolysis of methyl cyanoformate to HCN and monomethyl carbonic acid, which decomposes to CO₂ and MeOH. The time it takes to reach steady state depends on the rate of conversion of the fuel and decreases with increased conversion rate. Three catalysts, one metal catalyst and two enzymes, together constitute an efficient regulation system allowing control of the forward, backward and waste-forming steps, thereby assuring the production of high yields of products with high enantiopurity.